1. Field of the Invention
The technical field relates to a figure drawing apparatus, a control method of a figure drawing apparatus, and a recording medium.
2. Description of the Related Art
Conventionally, there is known a method of drawing a 3D (three-dimensional) stereoscopic figure. In this method, in a coordinate system of X, Y and Z, a Z coordinate corresponding to coordinates of (X, Y) is determined by a function of Z=f(x, y), and the coordinates of (X, Y, Z) are plotted as a 3D graph. This method of plotting the drawing of the stereoscopic figure as the 3D graph is a relatively easy arithmetic process and can be realized without requiring a high-speed, high-performance processor (CPU). However, it is not possible to easily draw a circular cylinder (including an elliptic cylinder), a circular cone (including an elliptical cone), a polygonal column, and a polygonal pyramid.
In addition, conventionally, as disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2005-182125, for instance, there is known a method of modeling surfaces of a stereoscopic figure as a set of polygons (grids). Not only any kind of stereoscopic figure can be drawn, but also processes such as movement, enlargement/reduction, inversion and rotation can be applied. However, the amount of arithmetic calculations becomes relatively large. This KOKAI Publication No. 2005-182125 does not particularly disclose a drawing process of a polygon which protrudes to the outside of a drawing area which is set separately.